In a number of commercial bioprocesses, mechanical cell disruption is used to release intracellular contents. This procedure releases all intracellular contents resulting in significant challenges in further downstream unit operations. For protein molecules in the periplasmic space of bacteria, a lab scale batch osmotic shock procedure has been used to selectively release the periplasmic contents without complete cell disruption. Such a process typically begins by equilibrating fermentation broth with high molarity salt or sugar solution (soak buffer) to build high osmotic pressure within the cells. This is followed by mixing with low osmolarity buffer (shock buffer) in a batch mode for a finite period of time for release of the periplasmic contents. Release is followed by removal of the cells by centrifugation. This traditional batch process is time consuming and has other limitations, such as difficulty in scaling up, accurate control of exposure time, and low throughput. These factors limit its applicability for the large scale release of molecules of interest. As such, methods and apparatus that overcome these limitations would be an improvement in the art.